<template>
  <transition :name="transitionName">
    <slot></slot>
  </transition>
</template>

<script>
export default {
  name: 'CssTransition',
  data () {
    return {
      transitionName: ''
    }
  },
  watch: { // 使用watch 监听$router的变化
    $route(to, from) {
      // 如果to索引大于from索引,判断为前进状态,反之则为后退状态
      if(to.meta.index > from.meta.index){
        // 设置动画名称
        this.transitionName = 'slide-left'
      }else{
        this.transitionName = 'slide-right'
      }
    }
  }
}
</script>

<style lang="stylus" scoped>
.slide-right-enter-active,
.slide-right-leave-active,
.slide-left-enter-active,
.slide-left-leave-active {
  will-change: transform;
  transition: all 500ms;
  position: absolute;
}
.slide-right-enter {
  opacity: 0;
  transform: scale(0.8);
}
.slide-right-leave-active {
  opacity: 0;
  transform: scale(1.2);
}
.slide-left-enter {
  opacity: 0;
  transform: scale(1.2);
}
.slide-left-leave-active {
  opacity: 0;
  transform: scale(0.8);
}
</style>
